Estimating chlorophyll‐a concentration using first‐derivative spectra in coastal water

Abstract

This study was intended to apply the technique of derivative analysis to estimate algal chlorophyll concentration in Pensacola Bay, Florida. The data collection was conducted over the 16 sampling sites on three separate occasions. A portable field spectroradiometer was used to collect the upwelling radiance of water and reference panel at each sampling station. The instrument records a continuous spectrum in 512 bands ranging from 350 nm to 1050 nm, with 1.37 nm spectral resolution. The first derivatives were computed and correlated with the chlorophyll‐a concentration. The results indicated the first derivatives at 630–645 nm, 660–670 nm, 680–687 nm and 700–735 nm were correlated strongly with chlorophyll‐a. The R values reached 0.858 for the wavelength at 686.7 nm. The results support the hypothesis that derivative spectra are less impacted by wave effects and, therefore, are an effective tool for estimating chlorophyll concentration.